My application will be having many microcontrollers with sensors monitoring a large area. The application requires all these microcontrollers to send the data to the master microcontroller. From the master microcontroller the data must go to desktop PC via serial connection and to a mobile application. Which one (Zigbee/GSM) will be suitable?
This completely depends on what you mean by "Wide Area." A few hundred square meters? A few hundred square kilometers? Zigbee is more cost effective and simpler to implement if you're within range. You could even mesh your nodes together to extend the collective reach of your network. Otherwise, well, you have no choice but to use something like GSM.
RF Line-of-sight range on readily available XBee Modules can be up to 2 miles. Higher power models can be had with 40 mile LOS range.
If you are within range, I would recommend ZigBee as that saves you the cost from having a sim-card in each device.
Buy zigbee modules that have SDK and HW ability for mesh networking. That will give you ability to talk to far nodes via routing nodes. Unfortunately zigbee can not do adhoc mesh networking so you need to know in advance what your routers will be, or to program your nodes routing your self. Another 802.15.4 module (by Synapse) can solve all this since it supports ad hoc mesh networking for you via SNAP protocol. It is not zigbee compatible, but Synapse modules are already adopted by big players like Garmin so this should not bother you. They also run much longer on batteries then zigbee modules. They can also give onboard analog and digital IO accessible without need for additional MCU (although you can connect it and give control to it if you wish). There is also USB stick that will enable your PC to talk to these modules.
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I want to know if it's possible to use a BLE module for both mesh networking and point-to-point connections at the same time.
Rationale:
The embedded linux (EL) product that I am designing needs to be able to connect to BLE peripherals like a heart rate monitor (sports grade, not medical) and the product needs to communicate with others of its kind.
I also need a very low power way of sending data from all EL devices to the internet. Ideally with only one of the products supplying a connection to the internet.
I am open to other solutions or reasons why this might not be a good approach even if it's possible.
Here is a rough block diagram of what I'm trying to achieve:
The block diagram does not show a HR connected to every EL device, however this would be a possibility as well.
Green = Embedded Linux Devices
Red = Heart Rate Monitors
Blue = An internet connection to the cloud
Yellow = connections between Embedded Devices
Option 1 - WiFi
The first option I considered was a wifi connection between the EL devices, however this will consume much more power than BLE.
Option 2 - BLE mesh
Using a BLE mesh seems like the best solution, if and only if, it's possible to do point-to-point connection at the same time.
Yes, this behaviour is specified in the BLE Mesh Profile specification in chapter 2.3.11. What you are looking for is a Proxy Node:
Proxy feature – the ability to receive and retransmit mesh messages between GATT and
advertising bearers.
Also take a look at the Ultimate Mesh Tutorial where they also describe the proxy node:
To allow communication with a mesh network from a non-mesh-supported BLE device, a special type of node called a proxy node can be utilized. A proxy node acts as an intermediary and utilizes GATT operations to allow other nodes outside of the mesh network to interface and interact with the network.
The protocol used in this case is called the proxy protocol, which is intended to be used with a connection-enabled device (using GATT).
This is of course hardware and software dependent. Not every hardware or software stack supports BLE mesh functionality.
The wikipedia article for Bluetooth mesh networking has a list of currently availible software stack supporting BLE mesh.
Context:
I am to do a project which is to compare ZigBee to Bluetooth Low Energy (BLE).
The parameters which the technologies are to be measured is RSSI over range and power consumption.
Both technologies/modules must be connected to a battery of some sort. Will be decided later in the project.
Both modules shall be controlled individually by a MCU/Arduino/Raspberry Pi which shall not be powered by the battery. So the only thing that should be powered by the battery is the ZigBee and BLE module.
I am considering to use the XBee 3 module as the ZigBee module. I'm aware that it comes with a BLE possibility aswell, but i need to evaluate two different modules, which is why i can't just use it both for the ZigBee and BLE testing.
This leads to the following questions:
(Questions are based on the context above)
Questions:
Any suggestions for BLE modules which are enable to sleep for several minutes before being pulled active again?
Any suggestions for ZigBee modules which operates in the 868MHz range, which is able to sleep for several minutes before being pulled active again?
Is there a problem with having the microcontroller connected to a different power-source than the ZigBee/BLE module?
Looking forward to your replies.
There are lots of options, but I'd recommend looking at Nordic Semiconductor's nRF528xx series and use the nRF52 DK, or Texas Instruments CC2640 series and use the CC2640R2F LaunchPad.
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Different power source is not a problem, but you need to have them referencing the same ground plane. If the distance between devices if more than a couple feet, you may need to do some isolation via optical or magnetic interfaces.
1) HM-10 board (CC2541 inside) might be a good option for what you are trying to do.
2) Zigbee S3B will do your work . you can select the module with required freq range
3) Yes, Different power sources is fine as long as every module has a common ground as already answered above
I have a fairly complex project done on Arduino2560, which I want to port to a standalone Atmega328. My problem is that one feature in the project is that it can communicate with my computer via serial (I made a C# program to handle it on the computer side, using the COM3 port). However, Arduino uses the USB communication for a virtual serial port, and I got a bit confused about how it could be done for the Atmega. It has the RX-TX lines, but what's next? Maybe use some serial-USB converters? What's the best approach for this? Is there anything I should be careful about?
Thanks.
Considering you mention a specific port COM3 on your computer I guess we can assume you have a native RS-232 port (one of those with the sub-D9 male connector that we were used to in the old days but are not so common anymore).
If that's the case, then you can get an RS232 level shifter. You'll just have to make the connections to RX, TX, Vcc, and GND and this device will change the RS-232 voltage levels to whatever your board requires (most likely 5V or 3.3V). Some (maybe most) high-end development boards include this kind of level shifter so maybe check yours in case you already have it (if you do you'll probably see a MAX232 IC somewhere). Or if you are crafty you can also DIY.
If you prefer to connect to a USB port (then, of course, it won't be COM3unless you explicitly change the configuration on Windows Device Manager) you can go for a USB-to-serial adaptor. On that front, you have many choices, starting from the cheapest at maybe 5$, but I'd rather choose one based on the FTDI chip, which is nowadays quite ubiquitous and has proven its reliability. This one is a good example, and at the same cost as the level shifter.
Now, are there any differences between using the native RS-232 or the USB adaptor? The answer is, for most practical purposes, no. If you go to the fine details, like buffer sizes, there will be differences, but if you need to go there you'll need to study the details in both cases to see if the port you have (or the one you're planning to add) meet your needs. For most scenarios, I would choose the USB, if only because you have it everywhere (most laptops don't have a native RS-232).
All of the above (based on RS-232 and/or USB) will work fine for cables running up to 5 meters (~15 ft.) for USB or maybe 10 to 15 meters (~30-45 ft.). This should be enough for most hobbyist or at-home projects. If you want to run longer cables you'll have to go for something like RS-485.
If you choose now the USB adaptor and you think you might need to relocate your board in the future to end up more than 20 meters (15 of RS-232 + 5 of USB) away from your computer just make sure your adaptor includes a TX Enable signal (TXEN). Most adaptors based on the FTDI chip will have this signal on a pin (like the one I linked above), and that will make your life way easier if you want to use RS-485 on a two-cable half-duplex bus.
EDIT: based on the feedback below there is new info that deserves a quick update.
First, you don't have an old school RS-232 port on your PC and second you have to design the connection on the microcontroller's side.
With that in mind it's clear you have to go for the USB solution. But you need to choose if you shift both sides to RS-232 levels or you stay at TTL. That decision depends again on the length of your bus. If it'll be really short (up to 2 meters) then you can stay on TTL, otherwise better shift to RS-232 to be on the safe side. There are many people who will tell you they have much longer serial links but how reliable they are you'll never know.
Since you have to design the board, I guess it makes sense to integrate the MAX232 and a sub D-9 connector there and get the cable you mentioned for your PC.
Or, you can add only a connector on the board and get the Sparkfun level shifter I linked above for the micro's side plus the same USB to RS-232 for your PC.
I would like establish a mesh network using Zigbee modules and ATmega8.
I need some basic c routines for establishing the network. My Controller is running with ATmega32. and end nodes will be on ATmega8.
I want plug and play wireless connection between Controller unit and nodes.
Please help me.
The Digi XBee series of RF modules is popular for plug and play wireless. In it's simplest configuration, a pair of modules operates as a serial cable replacement, with bytes going in on one module coming out on the other.
If you want to have a multi-node network, you'll have to use the radios in API mode, where frames include a header with addressing information and checksum in the footer. Digi has released an ANSI C XBee Host Library as Open Source on GitHub that could be a good starting point for that since you mention using C. It looks like there's even a fork of the library targeting the AVR platform.
#user2031622, zigbee nowdays has builtin microcontroller such as CC2530 provided by TI stack (Texas instruments).CC2530 has a inbuilt 8051 microcontroller which supports mesh networking.
What I have in mind is having a number of sensors (temperature, accelerometer, sound level meter) that are controlled by a micro controller. What I want to do is take this information and transmit it wireless to a laptop that will take this information and put it on to a web server using Zigbee. I don't know where to start.
Since you don't have any hardware as of yet, you might want to give the Arduino a try. The hardware is affordable, can be connected to your system via USB while being programmable in-system.
The basic board can be extended via so called "shields", which offer additional features. In your case, the XBee shield would be appropriate. Connecting your laptop to a XBee module is as simple as using Sparkfun's breakout board and a mini-USB cable.
The Arduino has a large community, so you will find a lot of resources, like books, online material, example code etc.
We also provide wireless modules that can be used for serial data transmission. They can be found at www.starmanelectric.com Our modules are very similar to the xbee, but more plug and play. They can be a great for going wireless for the first time. Our devices are designed to function like a "wireless cable" so if you're used to using wires then you'll be up and running in no time at all. We also have circuit examples for transmitting to a laptop serial port or USB. Any micro-controller will be fine for this application, as long as it has a serial port and a few ADCs to sample your data. Our modules also provide simple analog in/out which can run in parallel to the serial. If you want to compare to other systems, I would google "wireless serial modules"
Regards,
Michael
Starman Electric